1. Field of the Invention
The present invention relates to a tool for bore diameter work, used in bore diameter work such as, for example, boring, inserting grooves, and screw-cutting.
2. Description of the Related Art
Japanese Patent Application, First Publication, No. 11-277309 discloses one example of a conventional tool for bore diameter work of this type.
In this type of tool for bore diameter work, the flat base of a throw-away insert (hereinafter abbreviated as xe2x80x9cinsertxe2x80x9d), comprising a small-diameter rod-like section having a cutting-blade, is secured in a insert pocket at the tip portion of a long holder by a securing bolt which passes through the flat base; in addition, the side faces of the flat base are positioned by two wall faces, which stand out from the insert seat face of the insert pocket.
However, in the tool for bore diameter work described above, it is troublesome to insert and remove the insert, since the securing bolt which passes through the flat base of the insert must be extracted in order to do this.
Furthermore, since the side faces of the flat base are positioned by the two wall faces, which stand out from the insert seat face of the insert pocket, a slight difference between the shape of the insert pocket and the shape of the flat base reduces the installation rigidity of the insert, and any force sustained when carrying out cutting work (in particular, a force which is parallel to the flat base and perpendicular to the longitudinal direction of the holder) is liable to jolt the insert and reduce the positioning precision of the cutting-blade of the insert.
There are ways of increasing the installation rigidity of the insert, such as using a set bolt to press the side faces of the flat base as disclosed in Japanese Patent Application, First Publication, No. 2000-71113. However, this tool for bore diameter work has the same drawback that the insert cannot be inserted or removed without completely extracting the set bolt. Moreover, the use of the set bolt increases the number of components and makes the tool more troublesome to use.
Attempts have been made to facilitate the insertion and removal of the insert, such as in the tool for bore diameter work disclosed in Japanese Patent Application, First Publication, No. 2000-246515. However, since securing the insert in the holder by using the head of a clamp bolt to press a slope which is provided on the top face of the insert, there is point- or line-contact between the insert and the clamp bolt, and consequently, the problem of insert installation rigidity remains.
The present invention has been realized in view of the circumstances described above, and aims to provide a cutting tool in which the insert has high installation rigidity and can be easily removed and inserted.
In order to achieve the above objects, the tool for bore diameter work according to the present invention comprises a pair of insert restraining faces, provided opposite each other at a tip portion of a shank, which is pressed by a clamping unit so that the pair of insert restraining faces move closer to each other, thereby pressingly securing top and bottom faces of a throw-away insert, which directly contacts the paid of insert restraining faces. The throw-away insert comprises a substantially rod-like protrusion having a cutting-blade, which projects to the tip side of the shank. The pair of insert restraining faces have an indented or projecting V-shape parallel to the longitudinal direction of the shank, and the top and bottom faces of the throw-away insert have a projecting or indented V-shape which can connect with the pair of insert restraining faces.
According to this constitution, the insert is pressingly secured when the indented or projecting V-shaped insert restraining faces mesh with the top and bottom faces of the insert, which are shaped in correspondence therewith. Therefore, superior insert installation rigidity and insert positioning precision can be maintained.
Furthermore, since the insert restraining faces have indented or projecting V-shapes parallel to the longitudinal direction of the shank, the rigidity is especially strong against a force from the direction intersecting the longitudinal direction of the shank at the time of cutting.
Moreover, the pressing force exerted by the insert restraining faces against the top and bottom faces of the insert can be reduced by using a clamping unit to slightly loosen the clamp, thereby allowing the insert to be attached and removed easily and increasing workability.